In a warm climate, where you don't need to 'winterize' a sprinkler system, because of freezing water, all the piping, along with the valves, would be slip style, for speed of assembly. Flow controls on 2400's are a screwdriver-adjusted type. Not as handy as a handwheel type of flow control. They aren't essential.

Slip style is the way to go, faster installation and far less likely to cause problems such as leaks than the threaded valves...down the road. If you are going to use poly pipe for the lateral lines, they make valves with the barb fittings as well.